Goodwill And Other Intangible Assets (Summary Of Intangible Assets Subject To Amortization) (Details) (USD $)	3 Months Ended	12 Months Ended
	Jul. 31, 2014	Apr. 30, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 8,912,000	$ 8,912,000
Accumulated Amortization	3,410,760	3,309,246
Able [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	375,000	375,000
Accumulated Amortization	375,000	375,000
Able [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,395,000	2,395,000
Accumulated Amortization	2,395,000	2,395,000
Spitfire [Member] | Non-Contractual Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	12 years 9 months 18 days	13 years 1 month 6 days
Gross Carrying Amount	4,690,000	4,690,000
Accumulated Amortization	323,790	256,311
Spitfire [Member] | Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	22,000	22,000
Accumulated Amortization	22,000	22,000
Spitfire [Member] | Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	17 years 9 months 18 days	18 years 1 month 6 days
Gross Carrying Amount	980,000	980,000
Accumulated Amortization	106,158	93,909
Spitfire [Member] | Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	4 years 9 months 18 days	5 years 1 month 6 days
Gross Carrying Amount	50,000	50,000
Accumulated Amortization	15,470	13,685
Spitfire [Member] | Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	2 years 9 months 18 days	3 years 1 month 6 days
Gross Carrying Amount	400,000	400,000
Accumulated Amortization	$ 173,342	$ 153,341